Scorecardpy

* fixed a bug in function perf_eva

* fixed a bug in woebin function caused by pandas update (by CBravoR)
* suppressed warnings in woebin function caused by groupby operations (by CBravoR)
* added new functions vif, scorecard2

* fixed a bug in woebin function caused by the new function explode in pandas >= 0.25
* fixed a bug when intialzing binning
* modified the method to create initial fine binning breaks.

* fixed a bug in scorecard_ply, supports card as a DataFrame
* fixed a bug in woebin when using parallel in windows

* pdo in scorecard function now supports negative value.
* fixed a bug in split_df when the input dataframe has a specified index.
* split_df will not remove datetime and identical variables
* added a one-hot encoding function
* fixed a bug in woebin using chimerge method for int64 variables, causing it cant trnasform into woe values
* added save_breaks_list argument in both woebin and woebin_adj function, which can save breaks_list as file in current working directory.
* modified arguments in woebin, woebin_ply functions to fix some bugs

* added chimerge method for woe binning